This invention relates to aligning an optical fiber to a collimating lens.
Fiber optic systems often require aligning an optical fiber (xe2x80x9ca fiberxe2x80x9d) to couple light to an optical device, such as a lens or a sensor. The amount of light coupled is a function of the tolerance with which the fiber can be aligned to the optical device. Alignment stations are available which provide a method to xe2x80x98actively alignxe2x80x99 a fiber to an optical device. In this case, active alignment involves using actuators to physically move the optical device into alignment with the fiber based on optimizing a measured output signal from the optical device. Alignment stations are generally quite expensive and the alignment accuracy is highly dependent upon the skill of the individual operator. By comparison, passive alignment is defined as aligning a fiber to an optical device automatically, that is, according to the structure or shape of the members holding the fiber and the optical device.
According to an aspect of this invention an apparatus which holds an optical fiber in alignment to an optical device, the apparatus includes a fiber holder having a first plurality of indentations formed therein, an optical fiber within one of the first plurality of indentations, a base substrate having a second plurality of indentations formed into the base, a plurality of spacers, each of the plurality of spacers within a corresponding one of the second plurality of indentations, wherein the fiber holder is mounted on the base with the plurality of spacers within the first plurality of indentations, and an optical device mounted to the base.
One or more of the following features may also be included, wherein the optical device is a lens, wherein the first plurality of indentations includes an elongated groove, and wherein the optical fiber is held within the elongated groove, wherein the second plurality of indentations includes at least one trapezoidal-shaped pocket, wherein the second plurality of indentations includes an elongated groove, and wherein the optical device includes a lens mounted to the base within the elongated groove, wherein at least one of the plurality of spacers are spherically-shaped, wherein at least one of the plurality of spacers and the optical device are made of the same material, wherein the first plurality of indentations includes at least one trapezoidal-shaped pocket, wherein the second plurality of indentations includes at least one trapezoidal-shaped pocket, a single spacer mounted within one of the second plurality of indentations, wherein the fiber holder is mounted to the base in contact with the single spacer at an end of the fiber holder and establishes a horizontal position of the fiber holder, wherein one of the second plurality of indentations is formed to a different depth than a second of the second plurality of indentations, wherein the base further includes a third plurality of indentations formed in the base, and a second plurality of spacers, each of the second plurality of spacers within a corresponding one of the third plurality of indentations, wherein the optical device is mounted to the base in contact with at least two of the second plurality of spacers and establishes a horizontal position of the optical device, wherein the optical device has a round central section, wherein the optical device includes one of a dome-shaped lens and a disk-shaped lens, wherein the base further includes a third plurality of indentations formed in the base, and a second plurality of spacers, each of the second plurality of spacers within a corresponding one of the third plurality of indentations, wherein the optical device is mounted to the base in contact with at least three of the second plurality of spacers and establishes a vertical position of the optical device, wherein the optical device has at least one flat face, wherein the optical device includes one of a dome-shaped lens and a disk-shaped lens, wherein the second plurality of indentations formed in the base includes at least one indentation located adjacent to an edge of the base, and wherein one of the plurality of spacers held within the one indentation adjacent to the edge of the base protrudes beyond the edge of the base and establishes a known distance from a contact point on the spacer to a point on the base, wherein the one indentation adjacent to the edge of the base is a trapezoidal-shaped pocket, and wherein the one of the plurality of spacers held within the one indentation adjacent to the edge of the base contacts an interior wall of the trapezoidal-shaped pocket.
According to a further aspect of this invention an apparatus which holds a plurality of optical fibers in alignment to a plurality of optical devices, the apparatus includes a fiber holder having a first plurality of indentations formed therein, a plurality of optical fibers, each of the plurality of fibers within a corresponding one of the first plurality of indentations, a base substrate having a second plurality of indentations formed into the base, a plurality of spacers, each of the plurality of spacers within a corresponding one of the second plurality of indentations, wherein the fiber holder is mounted on the base with the plurality of spacers within the first plurality of indentations, and a plurality of optical devices mounted to an end of the fiber holder wherein each of the plurality of optical devices are aligned with a one of the plurality of optical fibers.
One or more of the following features may also be included, wherein at least one of the plurality of optical devices includes a lens.
According to a further aspect of this invention, a method of aligning optical devices includes mounting a first optical device on a first base having a partial indentation formed in an edge of the first base that holds a spacer to protrude beyond the edge of the first base and establishes a known distance from a point on the spacer to the first optical device, mounting a second optical device on a second base, and aligning the second optical device to the first optical device by placing the second base to contact the spacer held in the first base.
Embodiments of the alignment apparatus may have one or more of the following advantages. The apparatus enables an operator or user to passively align a fiber to a collimating lens and, if desired, it can be designed to precisely set the angle between the fiber and the lens so as to avoid back reflection of a transmitted light beam. The apparatus also enables an accurate determination of the distance from a spacer mounted on the side or end of the apparatus to an optical device, or the fiber, mounted on the apparatus.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.